1.Field of the Invention
The present invention relates generally to an inkjet printer, an ink billing system, and to a control method for an inkjet printer, and relates more particularly to an inkjet printer that can appropriately determine how much ink was used as a consumable for printing and can be used to form an ink billing system.
2.Description of the Related Art
Inkjet printers are generally used as image recording devices for recording images containing text and pictures, for example, on plain paper or other type of printing paper by depositing ink on the paper. An ink cartridge filled with ink is removably installed in this type of image recording device. When printing has consumed all available ink in the ink cartridge, a new cartridge can be installed to replenish the ink supply.
From the user's perspective, printing that consumes a large amount of ink is undesirable because of the operating cost, and printing using the least amount of ink while achieving the greatest expressive effect is therefore desirable. Depending upon the image data, high quality images can be printed using a small amount of ink. Simply changing the background from a dark color to a light color, for example, can reduce ink consumption while retaining high print quality without greatly changing the impression of the printed image.
As a way of reducing printing costs, Japanese Unexamined Patent Appl. Pub. JP-A-2003-228474 describes a printing system that, when a print job is received from the host computer, converts the print job to the print data that is required for printing by the print engine, estimates the total job cost required to print the print job using the print engine, and sends this estimated total job cost back to the host computer. The host computer in this printing system then presents this total job cost to the user and instructs the printing system to print the job only if the user asserts a print command.
Japanese Unexamined Patent Appl. Pub. JP-A-2003-228475 describes a printer that stores toner consumption and paper consumption data for each print job, calculates printer usage during a predetermined period for each user name, which is contained in each print job and identifies a particular user, and thus enables invoicing individual users an amount determined by printer usage.
Japanese Unexamined Patent Appl. Pub. JP-A-9-120345 describes a printer that stores the average toner consumption per pixel and the average pixel count per page in non-volatile memory, and has a function for calculating toner use from the number of pages actually printed and the number of pixels in the printed images.
Japanese Unexamined Patent Appl. Pub. JP-A-2001-175622 describes displaying detailed print job information including the status of the reception process, the print image conversion process, and the printing process for each print job, the host device that sent each print job and the communication path used to send the print job, use of consumables for each print job, and the content of any errors that occurred while processing a particular print job.
Japanese Unexamined Patent Appl. Pub. JP-A-2002-019212 describes storing printer status information such as the condition of the print engine, how much memory is available in the receive buffer, whether an error has occurred, and whether printer was successful for each page, and returning this status information to the host computer when requested.
The system described in Japanese Unexamined Patent Appl. Pub. JP-A-2003-228474 has the user confirm for each print job whether or not to proceed with printing. This works well in a relatively slow-paced environment where the printing frequency is not particularly high, but in commercial applications requiring fast, timely output such as issuing tickets, requiring user confirmation for each print job interferes with work.
Billing systems that invoice for ink consumption based on ink usage are available for ticket printing systems. When the same images are repeatedly printed, this type of billing system can preferably calculate ink consumption per ticket so that the user can select the images to be printed on each ticket to reduce the printing cost.
Such billing systems also assume that printing each job that is printed with ink is finished correctly and the output is usable. However, if printing is interrupted for some printer-side reason so that the job is not finished but the billing system charges for the unfinished job as though it was finished, the billing system will obviously seem unfair from the user's perspective.